Risk stratification for colon neoplasia: screening strategies using colonoscopy and computerized tomographic colonography

Gastroenterology. 2006 Oct;131(4):1011-9. doi: 10.1053/j.gastro.2006.08.015.


Background & aims: We developed a risk index to identify low-risk patients who may be screened for colorectal cancer with computerized tomographic colonography (CTC) instead of colonoscopy.

Methods: Asymptomatic persons aged 50 years or older who had undergone screening colonoscopy were randomized retrospectively to derivation (n = 1512) and validation (n = 1493) subgroups. We developed a risk index (based on age, sex, and family history) from the derivation group. The expected results of 3 screening strategies--universal colonoscopy, universal CTC, and a stratified strategy of colonoscopy for high-risk and CTC for low-risk patients--were then compared. Outcomes for the 3 strategies were extrapolated from the known colonic findings in each patient, using sensitivity/specificity values for CTC from the medical literature. Results were validated in the validation subgroup.

Results: In the derivation subgroup, universal colonoscopy detected 94% of advanced neoplasia and universal CTC detected only 70% and resulted in the largest total number of procedures and number of patients undergoing both procedures. The stratified strategy detected 92% of advanced neoplasia, requiring colonoscopy in 68% and CTC in 36% of patients, with only 4% having to undergo both procedures. In the validation subgroup, universal colonoscopy detected 94% and universal CTC detected 71% of advanced neoplasia, whereas the stratified strategy detected 89%, requiring colonoscopy in 64% and CTC in 40%. Unlike universal CTC, the stratified strategy was independent of assumptions for CTC sensitivity, specificity, and threshold for colonoscopy.

Conclusions: The stratified strategy based on our risk index may optimize the yield of colonoscopic resources and reduce the number of patients undergoing colonoscopy.

MeSH terms

  • Colonic Neoplasms / diagnostic imaging*
  • Colonic Neoplasms / epidemiology*
  • Colonic Neoplasms / pathology
  • Colonic Polyps / diagnostic imaging
  • Colonic Polyps / epidemiology
  • Colonic Polyps / pathology
  • Colonography, Computed Tomographic / economics
  • Colonography, Computed Tomographic / standards
  • Colonography, Computed Tomographic / statistics & numerical data*
  • Colonoscopy / economics
  • Colonoscopy / standards
  • Colonoscopy / statistics & numerical data*
  • Female
  • Health Care Costs
  • Humans
  • Male
  • Mass Screening / economics
  • Mass Screening / methods
  • Mass Screening / standards
  • Middle Aged
  • Reproducibility of Results
  • Retrospective Studies
  • Risk Factors
  • Sensitivity and Specificity